Snap-action electric switch



Nov. 137, 1964 G. J. BURY 3,157,758

SNAP-ACTION ELECTRIC SWITCH Filed March 19, 1962 GeoryeJ'Bury ATTY.

United States Patent 3,157 ,758 SNAP-ACTIGN ELECTRIC SWITCH George J. Bury, Chicago, Ill., assignor to Illinois Tool Works Inc, Chicago, 111., a corporation of Delaware Filed Mar. 19, 1962, Ser. No. 180,587 8 Claims. (Cl. 200-67) This invention relates in general to electrical switches and more particularly relates to snap acting switches.

Switches of the snap acting type have been manufactured heretofore which have been unduly complex in number of parts, have tight manufacturing tolerances, and have not presented the reliability and vibrational resistance required in many modern day applications. It is a general object of this invention to provide a switch which is rugged, simple to manufacture, has a minimum number of parts and which provides good vibrational resistance in field use.

It is a further object of this invention to provide a movable contact assembly having a movable member and a contact carrying member, the contact carrying member being pivoted on the movable member, there being biasing means to provide the snap action, as well as to provide a constant bias on the movable member toward engagement with resilient insulation means so that the switch in its at-rest or nonactuated position has good vibrational resistance.

It is a further object of this invention to provide a snap acting switch of the type abovedescribed which provides strong over-centering, a wide margin of over-travel and a good contact wiping action.

It is a further object of this invention to provide a switch wherein the tolerances are easy to maintain in mass production manufacture, does not require a stressed member to be flexed, which affords an increased range of materials available for manufacturing of the metallic parts of the switch, is easy to assemble by relatively unskilled labor and is otherwise well adapted for the purposes for which it was designed.

The novel features that are characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof may best be understood by the following description of a specific embodiment when read in connection with the accompanying drawings, in which:

FIG. 1 is a top plan view of the switch construction shown in FIG. 2;

FIG. 2 is a side elevational view of the switch shown in FIG. 1;

FIG. 3 is a side elevational view of another embodiment of the switch similar in many respects to the switch shown in FIGS. 1 and 2;

FIG. 4 is a detached view of one of the components shown in FIG. 2, the same part when used in the switch of FIG. 3 being bent and cut as shown by dot-dash lines as shall be explained;

FIG. 5 is a sectional view along lines 55 of FIG 4; and

FIG. 6 is a plan view of one of the components of the contact assembly in detached relationship.

The switch 10 is here shown as being of the open or the skeleton variety. It is to be undersood that this is to be considered illustrative rather than limiting inasmuch as the cooperating portions of the switch may be readily adapted to being enclosed in a housing.

The switch 10 essentially comprises an elongated thin metallic terminal member 12 which is substantially fiat throughout its entire extent which is spaced from a second terminal member 14 by suitable insulation means 20.

ice

The ends 16 and 18 of terminal members 12 and 14 may be offset relative to each other and apertured for ease of electrical connection as shown in FIG. 1. The members 12 and 14 are held in fixedly insulated relation by suitable rivets 22. On the end opposite to terminals 16 and 18, a movable contact means 24 is mounted for snap movement to and from a fixed contact means 26. The movable contact means 24 is mounted on terminal member 12 by an anchor means 28 and a pivotal connection means 30 in the form of a V-groove. The anchor means 28 comprises a pair of spaced apertures 32 and 34 which leave a small web 36, the web 36 being depressed from the top plane of member 12 as viewed in FIG. 2. In other words, portion 36 is a narrow neck intermediate to aperture 32 and 34.

The fixed contact means 26 is mounted on terminal member 14. The right hand end of terminal member 14 (as viewed in FIG. 2) has a number of angularly offset portions such as a first angularly offset portion 38, a second angularly offset portion 40 which together with a parallel arm third portion 44 and a bail fourth portion 42 form a somewhat U-shaped end for terminal member 14. Insulation means 46 may be disposed on the end of arm 44 for purposes to be later discussed.

It will be noted that the fixed contact means 26 mounted on arm 40 is disposed in a plane that is substantially at right angles to the plane of terminal member 12. It will also be noted that arm portion 44 is substantially parallel to arm 40 of member 14 and is spaced therefrom a predetermined distance.

The movable contact means 24 essentially comprises a first movable member 48, a coil spring biasing means 50 and a movable contact member 52. The movable contact member 52 has a contact 54 on the end thereof which is adapted to move from its at-rest position in engagement with the insulation means 46 to engagement with the fixedcontact 26 upon actuation of the movable contact means 24 as shall be later described. The movable contact member 52 is somewhat U-shaped in plan view as seen in FIG. 6 and comprises a pair of spaced parallel legs 56 and 58 having sharpened edges 60 and 62 on the ends thereof for pivotal coaction with the first movable member 48. A small aperture 64 is located intermediate the two legs 56 and 58 of the movable contact member 52 for attachment of one end of the coil spring biasing means 50, the other end being attached to the web or neck 36 of the anchor means 28 on blade member 12.

The movable member 48 has a first portion 65. a second portion 76 and a third portion 78 all in angularly offset relationship to each other. The first portion 65 is angularly deformed from and blanked out of the end of the movable member 48 to provide a pair of leg portions 66 and 68 having V-shaped notches '70 and 72 therein for receipt of the ends 60 and 62 of the movable con-tact'blade 52. The second portion 76 of movable member 48 comprises a pair of spaced legs 80 and 82 having V-shaped ends 84 and 86 which coact the V-shaped pivotal notch 30 on the end of member 16. It will be noted that legs 80 and 82 are spaced apart further than are legs 66-68, which aids in giving stability to the movable member 48 upon pivotal movement thereof about V-shaped ends 84-86. It will also be noted that notches -72 extend a greater distance from the juncture of portions 65-76 than do ends 84-86.

The long third portion 78 of member 48 is angularly offset by a slight angle from the plane of second portion 76. This may be adjusted within limits as suitable and desired so as to maintain the contact 54 in engagement with the insulation means 46 and the third portion 78 in engagement with insulation means 46 on the opposite side of arm 44.

Movement of the third portion 7 8 of the first movable member 48 to the right (as viewed in FIG. 2) will cause the movable contact 54 to snap into engagement with the fixed contact 26. This occurs because the pivot point 70 moves over center. However, the geometry is such that upon movement of the third portion 78 to the right as viewed in FIG. 2, the movable member 48 is still always biased toward engagement with the insulation means 46 which serves the functions of providing a stop for movable member 48, insulates the contact 54 to interrupt an elec- 'trical current through mcmber 18, and also serves as a resilient member to absorb vibrations which might tend to cause unauthorized actuation of the switch. The insulation means 46 is preferably formed of nylon or a similar plastic material. Alternatively to the construction shown, the plastic member 46 may be in button form so that it extends on either side of arm portion 44 of member 14.

Extreme actuation'or overtravel of portion 78 of member 48 to the right as viewed in FIG. 2 will eventually cause contact member 52 to engage the insulation 46 as the contact 54pivots on the fixed contact 26. This provides an outer limit or stop, preventing the assembly from inadvertent disassembly. Stated another way, the blade 52, upon extreme overtravel to the right of the member 43 about pivot point 36), will cause member 52 (at about the aperture 64) to engage the-insulation means 46 prior to portions 66 and 62 leaving the notches 70 and '72 in portion 65 and, thus, the assembly will not become disassembled inadvertently.

Due to the geometry shown, a relatively short movement of the movable member 48 will cause the contact blade 52 to snap over center. T his may be varied to suit and depending upon the amount of pre-travel and overtravel desired. The changing of the relative lengths of portions 65, 76 and 78 will provide the desired characteristics.

It will be apparent that the lower end of portion 78 of the movable member 48 may be actuated manually or by some other mechanism as suitable-and desired. Further, the movable member 48 may be made-entirely of relativelyhard plastic such as nylon since the current may go from the movable contact blade 52 through the spring 50 to the anchor means 34, thence along member 12 to the terminal 16. However, this is possible only for low current applications and requires a special spring 50 which would be made of beryllium copper. When the movable member 48 is configured out of plastic, it is not necessary to have a separate insulation means 46 of the type shown in FIG. 2. It will also be apparent that the insulation means 46 may be disposed upon the portion 78 of the movable member 48 so as to engage member 14 rather than the reverse as shown. When this is done, an end portion 96 such as shown on member 12a of switch a becomes necessary for prevention of shorting on extreme overtravel.

The alternate embodiment shown in FIG. 3 is substantially similar to that shown in FIG. 2 and similar parts will be given similar reference numerals with the addition of the sufi'ix a. Only thedifferent characteristics of the switch .in FIG. 3 will be discussed. The switch 10a is a double pole switch in distinction to the single pole switch shown in FIGS. 1 and 2. A third terminal member 88 is inserted intermediate the terminal members 12a and 14a. It will be noted that the terminal member 14a has the bail portion 42a slightly wider than portion 42 so that arm portions 40a. and 44a are spaced apart a greater distance than in the embodiment shown in FIG. 2. The member 88 an angle portion 90 having a fixed contact 92 on the end thereof, which corresponds in a sense to the fixed contact 26. The second fixed contact 94 is fixed on the arm 44a in place of the insulation means. Member 12a now becomes a common terminal of the switch and actuation of the arm 98 of movable member 48a will cause actuation of the contact 54a between contacts 94 and 92.

The movable member 4311 differs slightly from that shown in FIG. 2 in that the lower portion thereof is cut out along lines 100, 1132 and 104 as shown in dotted lines on FIG. 5. The tongue portion so formed then is apertured at 106 and bent along lines 108-110 to the position and configuration shown in FIG. 3. This permits a different actuation of member 48a but substantially the same considerations will apply. The insulation means 461: in the form of a plastic button is mounted in aperture 106 to serve essentially the same functions as does the insulation 46 in FIG. 2. The upturned end 96 on member 12a prevents overtravel of member 43a to a position where blade 52a. would short out contacts 92 and 94.

Although specific embodiments of the invention have been shown and described, it is with full awareness that many modifications thereof are possible. The invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

What is claimed as the invention is:

1. A switch comprising a first electrical terminal member, said first eiectrical terminal member being formed with a U-shaped end portion providing a pair of generally parallel spaced first and second arms connected by a bail portion, first fixed contact means mounted on one of said first and second parallel arms of said electrical terminal member, a second electrical terminal member having anchor means and pivot means formed therein, movable contact means comprising spring means, a first movable member connected with said pivot means and a contact carrying member pivotally mounted on said first movable member, said spring means engaging said contact carrying member and said anchor means of said second electrical terminal member to maintain the pivotal connection between said contact carrying member and said first movable member and the pivotal connection between said first movable member and said pivot means in said second electrical terminal member, said spring means further providing asnap action movement to said movable contact carrying member upon over center movement of the pivotal connection between the contact carrying member and the first movable member, said spring means constantly biasing said first movable member toward engagement with said first electrical terminal member.

'2. The switch set forth in claim 1 wherein a third electrical terminal member having second fixed contact and said first electrical terminal means to insulate one from the other and afford an impact absorbing means for preventing undesired actuation of said first movable member and thereby said contact carrying member.

4. The switch set forth in claim 1 wherein insulation means is disposed relative to said first arm and said first movable member to prevent electrical contact therewith.

5. The switch set forth in claim 4 wherein said first fixed contact means is mounted on said second arm, and said insulation means is mounted on said first arm, both said first and second arms being disposed substantially transverse to the plane of said second electrical terminal member in the vicinity of said anchor means.

6. The switch set forth in claim 5 wherein said first movable member has first, second and third integral portions, said first portion being angularly disposed relative to said second portion and engageable with said pivot means in said second electrical terminal member, said second portion being disposed substantially parallel to said plane of said second terminal member at said anchor means and intermediate said anchor means and said first and second arm portions of said first terminal member, said second portion being formed with pivot means for coaction with said movable contact member, and said third portion being engageable with said insulation means which is mounted on said first arm.

7. A relatively open skeleton type switch comprising, first and second relatively thin elongated metallic elements spaced from each other by first insulation means adjacent one end thereof and at least one of said elements carrying a fixed contact means on the other end thereof and the other of said elements being substantially straight and having anchor means and pivot means spaced apart there on, movable contact means having a first position and movable to a second position relative to said fixed contact means, said movable contact means comprising spring means, a first movable member engaged with said pivot means for movement between an at-rest position and an actuated position and including an arm portion extending angularly therefrom with a pivot connection spaced from and generally aligned with said anchor means, and a contact carrying member pivoted to the pivot connection on said arm portion, said spring means engaging said contact carrying member and said anchor means to maintain the pivotal connection between said contact carrying member and said first movable member and to provide a snap action to movement of said movable contact means upon over center movement of the pivot connection between said arm portion and the contact carrying member, said first movable member being engageable by operator means to afford movement thereof from its at-rest position.

8. A switch as claimed in claim 7, wherein resilient insulation means .is mounted for engagement between one of said elements and one of said members to afford vibrational resistance to unintended actuation of the said one member.

References Cited by the Examiner UNITED STATES PATENTS 2,728,826 12/55 Lander 200-67 2,800,546 7/57 Reitler 200--67 2,905,785 9/59 Quinn 20067 3,001,042 9/61 Cherry 200-67 3,114,805 12/63 Baumer 200-67 BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner. 

7. A RELATIVELY OPEN SKELETON TYPE SWITCH COMPRISING, FIRST AND SECOND RELATIVELY THIN ELONGATED METALLIC ELEMENTS SPACED FROM EACH OTHER BY FIRST INSULATION MEANS ADJACENT ONE END THEREOF AND AT LEAST ONE OF SAID ELEMENTS CARRYING A FIXED CONTACT MEANS ON THE OTHER END THEREOF AND THE OTHER OF SAID ELEMENTS BEING SUBSTANTIALLY STRAIGHT AND HAVING ANCHOR MEANS AND PIVOT MEANS SPACED APART THEREON, MOVABLE CONTACT MEANS HAVING A FIRST POSITION AND MOVABLE TO A SECOND POSITION RELATIVE TO SAID FIXED CONTACT MEANS, SAID MOVABLE CONTACT MEANS COMPRISING SPRING MEANS, A FIRST MOVABLE MEMBER ENGAGED WITH SAID PIVOT MEANS FOR MOVEMENT BETWEEN AN AT-REST POSITION AND AN ACTUATED POSITION AND INCLUDING AN ARM PORTION EXTENDING ANGULARLY THEREFROM WITH A PIVOT CONNECTION SPACED FROM AND GENERALLY ALIGNED WITH SAID ANCHOR MEANS, AND A CONTACT CARRYING MEMBER PIVOTED TO THE PIVOT CONNECTION ON SAID ARM PORTION, SAID SPRING MEANS ENGAGING SAID CONTACT CARRYING MEMBER AND SAID ANCHOR MEANS TO MAINTAIN THE PIVOTAL CONNECTION BETWEEN SAID CONTACT CARRYING MEMBER AND SAID FIRST MOVABLE MEMBER AND TO PROVIDE A SNAP ACTION TO MOVEMENT OF SAID MOVABLE CONTACT MEANS UPON OVER CENTER MOVEMENT OF THE PIVOT CONNECTION BETWEEN SAID ARM PORTION AND THE CONTACT CARRYING MEMBER, SAID FIRST MOVABLE MEMBER BEING ENGAGEABLE BY OPERATOR MEANS TO AFFORD MOVEMENT THEREOF FROM ITS AT-REST POSITION. 